Convertible airplane



Malth 19, 1935. G, M. BELLANCA 1,995,090

CONVERTIBLE AIRPLANE Filed Sept. 2, 1952 @at r Patented Mar. 19, 1935 Application September 2,

1932, sesame. 631,550

9 .Claima (Cl. 244-12) This invention relatesto aircraft and more particularly to a convertible airplane. f An object o f the present invention is to provide an airplane ofthe convertible type. 1

Another object is to provide an airplane which may'ireadly be converted from substantiallya monoplane` to a biplane type. x

Anotherobject is to devise an airplane of stand-I ard type which may readily and easily be modified to increase its load carrying characteristics.

With these and "otherequally important objects in View the inventioncomprehends the concept of providing vanV airplane of improved design by reason of which it may readily be converted, by adding airfoilfsurfaces, to a different type hav- Y in'gan increased carrying capacity.v In orderto enable a `ready comprehension of the invention, physical embodiments are shown in theaccompanyingdrawing, in'ivhich:

Fig. 1 is a front elevation of one form ofairplaneconstructed accordingY to the present invention. jV y i Fig. `2 isa View similar toFig. l showing the airplaneof Fig. 1 converted to anothertype. u

Figs. 3 andi are similar to Figs. l1 and 2 respectively of a specicallydierent design of airplane. 1 y

In certain airplanes, particularly intheA military type, it has been found desirable toprovide one Whichin essential features is standardized but which mayreadily beV converted so" asY to adapt it to other purposes. Forexampla'it has been found desirable to provide an airplane which may be simply modied so as-to function either as a pursuit plane ora bombing plane.` 'has become particularly true in View of the re-' cent developmentstending toward the production of very high speed bombers. y

`In accordance Withthepresent invention a standard plane Inlay be produced which, by a very slight modification in structure, may be modified so as to adapt itto arelatively Wide eld of use. Atypical embodiment of such a concept is shown in Figsl and 2 The airplane, for example, may comprise a fuselage lprovided Vwith a suitable power plant and drivenby' the tractor propeller 2. The plane is provided with the main wing sections 3` and'4 permanently secured to the upper portion ofthe fuselage. Preferably these are of gull shape, that is to say are formed with root sections 3' and 4 which are displaced from the main plane of the Wing.` Such a construction provides improved vision.

To improve the maneuyerability and generally to give the desirable characteristics of biplane Vdynamic characteristics' of a biplane.

construction, stub wings 5 and 6 are permanently attached to a lower portion of the fuselage.

AThese may be of any desired span and cord and may or may not be staggered with respect to the upper wing. Preferably the wing structure is rigidirled and generally improved by interconnecting the stub Wings and main Wingsvby the interplane struts 7 and 'l'. Such a structure, as Will be appreciatedfpresents the essential aero- InY some circumstances it is advantageous to utilize a plane such as that described for purposes in .which increased stability 'isdesired A typical Y Y Vdescribed above, Vthe Wing tips `5 and 67 may be removed and'to the exposed Wing tips may then beattached the lift struts 8 Yand 8. 'I'he end of the lift struts 8 and 8v are attached to the undersideiof the main Wings and preferably to fix tures permanently attached to the leading Vand trailing spars thereof. The lift struts 8 and 8 may Ycomprise stock construction so as to'be immediately available for attachment to the biplaneof Fig. 1. r After the attachment of the lift struts the vplane is thenconverted` into one of the sesqui-plane type, having considerably improved lateral stability. Thelift struts may be of any desired shape and aspectvratio. The planes ofFigs. 1 and 2 may be provided with any suitable type of landing gear, indicated generally at 9. With such a conversion the load carrying factor of the plane is considerably increased and, as noted above, th lateral stability considerably enhanced.

Such extensions ofthe potential use of a standard plane may be achieved in other specific structures, such for example as in a plane of the type shown vin Fig. 3'.V Such airplane may, like'the plane previously described,` comprise a fuselage l driven'bya tractor propeller 2 and havingA the main 4sustenation surfaces 3 and 4. In this type of plane the stub Wings l0 and 11 `are provided which are permanently secured toV a lower portion of the fuselage. These are set at a rather decidednegative dihedral and, like the stub Wings 5 fand 6, may be of any desired aspect ratio. 'Ihese Wings preferably are of rugged construction and are adapted to directly carry the landing Wheels 12 and 13. To the end of each of the stub .Wings 10 and 11 are connected respectively the lift struts 14 and 15. The joints between the stub wings, lift struts and the landing wheel fixtures are completely faired by fairing 16. This fairing has a detachable section 17 which may readily be removed, exposing the tip or end of the stub wing. This tip or end is provided with permanent fixtures, such as hinge fixtures. When it is desired to convert such an airplane the covers 17 may-be removed and the supplementalwings 18 and 19 mounted. if desired, suitable guy wires or interplane struts may be attached at one end to the wings 18 and 19 and at the other ends to any suitable portion of the plane to impart increased strength and rigidity. Such a 'plane when converted is adapted to a wider use. `After the attachment of the supplemental wings' 18 and 19, which may ofcourse be of any desired span, the plane comprises essentially a biplane, the lower planes of whichinclude an internal negativeI dihedral section and an external substantially horizontal section. The lift struts 14 and 15.-besides giving increased lift to the plane, serve to strengthen and rigidify the lower wings, serving as they do to take both landing and flying stresses. The lower wings 18 and 19 may be suitably conformed soas to serve as carriers for load 2O Which, for example, may comprise bombs or other articles. t will-be seen that such a type-of plane presents Very high load carrying characteristics and may be converted from-a standard planelof simple and lrugged construction.

While typical embodiments of the invention have been shown, these are given merely as examples of thel underlying principles involved. They are, therefore, lnot considered toY restrict the invention beyond the restrictions clearly imposedby the appended claims.

.I claim:

` I1. An airplanecomprising al fuselage, main wingsections attached to the upperportionof the fuselage, stub wings of' .negative dihedral permanently secured rto the lower portion of the fuselage and a supplemental wing detachably securedto the stub wing and extending horizontally therefrom and means on :the supplemental wing to detachably secure loads thereto.

airplane comprising` a fuselage, main wingf sections attached tothe upperportion vof the fuselage, stub wingsy of negative dihedral permanentlysecured vto a Alower portion ofthe fuselage, strut wings attached at one'end to the. mainV wing and atthezother to an end of the; stub wing, and a supplemental wing section detachably secured tothe stulowing and extending. laterally therefrom. i

3., An airplane comprising a fuselage, main Wing sections secured to the upper` portion `of the fuselage, stub wings of negativedihedral secured to the lower portion of the fuselage, lift struts connected at one end -tothe tipof the stub'wing andat the other to an underside of the main wing, and `supplemental wings detachably `secured to the stub wings and yextending ksubstantially horizontally therefrom.

yfinan Vairplane lcomprisingV a fuselage, main wing sections. attached t0 Vthe upper portion '0f the fuselage, stub wing sections of negative dihedral permanently secured to a lower portion of the fuselage, strut wings permanently secured, at one end to the stub wing and at the other to the under side of the main wing, and a supplemental wing section detachably secured to the stub wing adjacent the point of connection of the strut wing thereto, said supplemental wing extending substantially horizontally from the stub wing.

Y5; An airplane comprising a fuselage, main wing sections attached to the upper portion of the fuselage, stub wing sections permanently secured to a lower portion ofthe fuselage, strut kwings permanently secured, at one end to the stub'wing and at the other to the under side of the main wing, and a supplemental Wing section detachably secured to the stub wing adjacent the point of connection of strut wing thereto, said supplemental wing extending substantially horizontally from the stub wing.

6. An airplane vcomprising a fuselage, .main Wing sections attached to the upper portionof the fuselage, stub wing sections of negative dihedral .permanently secured to a lowerportion ofthe fuselage, strutk wings permanently secured, at one end to the stub ywing andy at the otherend. tothe under side of the main wing and a supplemental wing section of relatively shorterY span than themainwingsection detachably secured to the stub wingV adjacent vthe point of connection ofthe strut wing thereto, said supplemental wing extending substantially horizontally from the stub wing. Y

7. An vairplane comprisingA a fuselage, main Wing-sections attached to the upper portion of the fuselage, stub wings of Vrelatively shorter span than the main wing permanently secured to the lower portion of fuselage, landing wheels secured tothe stub'wings adjacent their extremities'strut Wings permanently secured, at one end tothe extremity of the stub wing and at theother to the under side of the main wing, and a supplemental wing section of a relatively short span detachably 'secured to the stub Wing adjacent the point of connection .of the--strut wing thereto.

8. An airplane comprising a fuselage, main Wing sections attached to the upper portion of the fuselage, stub wing sections 'Permanently secured `toa lower portion of the fuselage, strut wings permanently secured at one end to the stub Wingiandat the-other to` the underside of the main wing, and aY supplemental wing section detachably secured adjacent the point-of. connection of the strut wing and stub'wings, said supplemental wing section extending ksubstantiallyV horizontally from the stub'wing. y

9. An airplane comprisingv a fuselage, main Wing sections attached to the upper portion of the fuselagefstub Wings ofnegative dihedral permanently secured to a lower portion of the fuseilage, strut wings attached atone end to the vmain-.wing and. atthe'other to an end of the stub Wing, and a supplemental wing section detachably secured adjacent the point of connection .of the stub wing and strut Wing and extending laterally from the stub wing.

GIUSEPPE M. ,BELLANCA 

